A259193 5x + 1 sequence beginning at 11.

11, 56, 28, 14, 7, 36, 18, 9, 46, 23, 116, 58, 29, 146, 73, 366, 183, 916, 458, 229, 1146, 573, 2866, 1433, 7166, 3583, 17916, 8958, 4479, 22396, 11198, 5599, 27996, 13998, 6999, 34996, 17498, 8749, 43746, 21873, 109366, 54683, 273416, 136708, 68354, 34177, 170886, 85443

Offset

0,1

Links

Alonso del Arte, Table of n, a(n) for n = 0..999

Alex V. Kontorovich & Jeffrey C. Lagarias, Stochastic Models for the 3x+1 and 5x+1 Problems arXiv:0910.1944 [math.NT], 2009.

Formula

a(0) = 11; a(n) = 5a(n - 1) + 1 if a(n - 1) is odd, a(n) = a(n - 1)/2 otherwise.

Example

11 is odd, so it's followed by 5 * 11 + 1 = 56.
56 is even, so it's followed by 56/2 = 28.

Mathematica

NestList[If[EvenQ[#], #/2, 5# + 1] &, 5, 100]

Prog

(Magma) [n eq 1 select 11 else IsOdd(Self(n-1)) select 5*Self(n-1)+1 else Self(n-1) div 2: n in [1..80]]; // Vincenzo Librandi, Jul 04 2015

Crossrefs

Cf. A259207, A057688.

Sequence in context: A032166 A218000 A206528 * A099532 A041226 A042503

Adjacent sequences: A259190 A259191 A259192 * A259194 A259195 A259196

Keyword

nonn,easy

Author

Alonso del Arte, Jun 21 2015

Status

approved